This invention relates to pyrographic printers and, more particularly, to exhaust systems for disposing of the gaseous and solid waste products produced by electroresistive printing processes and the like.
Electroresistive printing is one of the better known pyrographic printing processes. It basically involves controlling the current flow between a stylus and a conductive substrate for an electroresistive recording medium to burn off localized areas of an overcoating on the recording medium, thereby exposing a contrasting underlying layer in an image configuration. As a general rule, there is relative motion between the stylus and the recording medium so that the stylus traverses the recording medium in accordance with a predetermined scanning pattern. For example, in the Xerox 400 Telecopier and Telecopier 410 facsimile transceivers, which are manufactured and sold by Xerox Corporation, electroresistive paper is wrapped on a rotating drum to be more or less helically scanned by a stylus which is advanced axially of the drum.
Unfortunately, eletroresistive and other pyrographic printing processes are accompanied by the release of waste products, including aromatic gases, visible smoke, and particulate matter. The aromatics create objectionable odors, while the smoke and particulate matter tend to deposit a soot-like residue.
Others have already recognized that the environment contamination attributable to the waste products of pyrographic printing can be reduced, if not completely eliminated, by suitable exhaust systems. A case in point is the Xerox Telecopier 410 units which have exhaust systems of the type described and claimed in a commonly assigned U.S. Pat. No. 3,840,880 which issued Oct. 8, 1974 on an application of Hans Peter Kramell entitled "Filtering System for Pyrographic Recorders." Indeed, to simplify this disclosure, that patent is hereby incorporated by reference.